1. Field of the Invention
This invention relates to an improved method for transporting hydrocarbons thru a pipeline or wellbore. More particularly, this invention relates to the introduction into a pipeline of a viscous hydrocarbon or mixture of hydrocarbons together with an aqueous solution of an anionic surfactant and an alkalinity agent whereby a low viscosity, salt-tolerant oil-in-water emulsion is formed which facilitates movement of the hydrocarbon in the pipeline. Optionally, the solution may contain a guanidine salt or an oxyalkylated, nitrogen-containing aromatic compound to aid in the formation of salt-tolerant oil-in-water emulsion.
2. Description of the Prior Art
The transportation of heavy crudes by pipeline is difficult because of their low mobility and high viscosity. The usual methods to facilitate the flow of heavy crudes have included cutting them with lighter fractions of hydrocarbons. However, the procedures involve the use of relatively large amounts of expensive hydrocarbon solvents to transport a relatively cheap product. The practice also necessarily requires the availability of the cutting hydrocarbon solvents which, in some instances is inconvenient.
Another method to assist the flow of hydrocarbons in pipeline is the installation of heating equipment at frequent intervals along the pipeline, whereby the crude is heated to reduce its viscosity and thereby facilitate its transport.
Heaters employed for this purpose can be operated by withdrawing some of the crude being transported for use as fuel. However, this procedure may result in the loss of as much as 15 to 20% of the crude being transported.
Other methods to facilitate transport of heavy crudes have employed thermal viscosity breaking, which, however, produces substantial amounts of gas.
It is known that substantial amounts of water may be introduced into a pipeline containing a stream of viscous crude flowing therethru to reduce the drag on the stream and thus facilitate the flow thru the pipeline. This has been done by the addition of water together with crude into the pipeline such that a water-in-oil emulsion is formed.
It is thus an object of the present invention to provide a transport method for viscous crudes which are difficult to emulsify especially in the presence of water with substantial salt content whereby they can be more easily transported by pipeline at a high thru-put rate.